Key seat cutter



C. O. VAN NOTE, JR

- Jan. 28, 1958 KEY SEAT CUTTER Filed Dec. '7, 195's Gttorneg UnitedStates Patent ice KEY SEAT CUTTER Charles 0. Van Note, Jr., Palos VerdesEstates, CaliL, assignor to Servco Engineering, Ltd., Long Beach, Califa corporation of California Application December 7, 1953, Serial No.396,654

2 Claims. (Cl. 255-27) This invention relates to a tool for cutting andthereby enlarging a key seat in a well bore and which seat frequentlyacts to prevent upward retraction of the drilling tool on the end of along string.

In the rotary drilling of wells, particularly deep wells, the drillstring, because of its great length, flexes to wear a groove or key seatin the side wall of the bore. The string being of smaller diameter thanthe drill collar at the end thereof, forms a seat that is smaller indiameter than the diameter of the drill collar. Consequently, it isrlifiicult and frequently impossible to withdraw the drill 2,821,363 VPatented Jan. 28, 1958 weight of the string to act on a reaming collarthat is wedged in a key seat and jar the same loose.

A further object of the invention is to provide a key seat cutter thatincludes a reaming sleeve that can be worked upwardly through a key seatin successive stages by eifecting successive enlargements of the keyseat.

The invention also has for its objects to provide such means that arepositive in operation, convenient in use, easily installed in a workingposition and easily disconnec'ted therefrom, economical of manufacture,relatively from the bore because the same becomes wedged in the 1 as thestring is withdrawn up- Prior jar tools usually embody a reaming sleevethat D A is either keyed to a mandrel on which mounted to, at all times,turn with the mandrel, or is rotationally free of the mandrel andincapable of being rotated. Another object of the invention is toprovide a key seat cutting tool that is provided with a reaming sleevethat may be keyed to or freed from the mandrel, as desired, therebyenabling determination as to whether or not the sleeve is stuck orwedged in a key seat.

Another object of the invention is to provide key seat cutter means thatemploys both the weight of a drill string and the stored energy thereinthat results from placing said string in torsion to obtain a suddenrelease between the string and a member that is wedged in a key seatand, thereby, create a sharp and powerful member-dislodging force thatfrees the latter from the seat in which wedged.

.If any point of a drill string becomes wedged or seized in a well bore,that portion of the string above the point of such seizure and extendingto the surface of the bore is capable of being torsionally wound fromthe surface, thereby imparting a strong torsional force on said portionof the string. If this torsion is being held or retained by a releasableconnection between a member that is seized in the bore and the stringitself, and release of the connection may be effected by an increase ofthe force of weight of the wound-up string portion upon said connection,then, by holding the torsion from above and at the same time loweringthe string, the weight of the latter, when suddenly released, allows thestring to drop with a strong jarring force that acts on the seizedmember in a direction to downwardly dislodge the same. Accordingly, astill further object of the invention is to provide novel and improvedreleasing means as above indicated, that is effective, under the forcesapplied'by the weight and torsion on a drill string, to suddenly releasethe simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novelcombinations and arrangements of parts, which will more fully appear inthe course of the following description. However, the drawing merelyshows and the following description merely describes, one embodiment ofthe present invention, which is given by way of illustration or exampleonly.

In the drawing, like reference characters designate similar parts in theseveral views.

Fig. 1 is a partial elevational and partial sectional view of a key seatcutter according to the present invention.

Fig. 2 is a similar view showing the cutter in another position.

Figs. 3 and 4 are enlarged cross-sectional views as taken on lines 33and 4-4, respectively, of Fig. 1.

Fig. 5 is a similarly enlarged longitudinal sectional view of the lowerend of a reaming sleeve shown in the other figures.

The key seat cutter that is illustrated comprises, generally, a mandrel10 provided adjacent its lower end with key means 11, and a reamingcollar or sleeve 12 on said mandrel 10 and provided with means 13cooperating with the key means 11 to keythe sleeve to the mandrel orrelease the same, as desired.

The mandrel 10 is formed as an element of a drill string 14 which, inthe usual manner, carries a drill collar 15 at its lower end. Whileshown with a pin 16 directly engaged in the box 17 of said drill collar,a portion of the drill string may be interposed so that mandrel 10 isspaced above the drill collar, as desired. A similar pin and box isprovided between the upper end of the mandrel and the lower end of thedrill string 14.

The mandrel 10 that is illustrated comprises an eloni gatedround-sectioned stem 18, an enlarged portion 19 at the upper end of saidstem defining a downwardly-facing annular shoulder 20, and an enlargedportion 21 at the lower end of the stem defining an upwardly-facingannular shoulder 22. In practice, portion 19 is made of a diametral sizeapproximating the largest diameter of the drillstrong 14 and portion 21of a diametral size approximating that of drill collar 15. Since thedrill collar is usually substantially larger than the drill string,shoul-,

der 22 is larger in diameter than shoulder 20. Also, the

mandrel is axially hollow as indicated at 23, to, providev the usualpassage for fluid circulated through the drill string.

The key means 11 is shown as diametricallyopposite keys 24 that arepreferably integrally formed on stem 18 adjacent but in spaced relationto shoulder 22 Each q machined to its smaller size from the initiallarger size of portion 21. In some cases, sutficient strength may beachieved by welding said keys 24 onto stem 18.

The reaming sleeve or collar 12 comprises a tubular member that issubstantially shorter than mandrel stem- 18 and, in order to assemblethe same onto the stem, is initially formed as two similar longitudinalhalves that are connected by welds 27, asbest seen in Fig. 3.

The upper end 28 of reaming. collar 12 is formed to be of approximatelythe diametral size of mandrel part 19 and the lower end 29 of thediametral size of the larger mandrel part 21. As shown, said collar maybe provided with an intermediate part 30 that has a diametral sizebetween that of collar ends 28 and 29 and it will be obvious that saidintermediate part 30 may be omitted or two or more differently sizedintermediate parts may be provided. In any case, the reaming collar 12is formed as a stepped tubular member that is enlarged in successivestages from the top down, the increments of enlargement depending on thenumber of stepped parts and the difference in diametral size of mandrelparts 19 and 21.- Each stepped part of the collar 12 is preferablyprovided with reaming projections 31 which may vary in their form andare designed to enlarge a key seat when rotated therein. In this case,the reaming projections on the smaller collar end 28 are made of suchsize as to enlarge a key seat to the approximate size of intermediatecollar part 30, and the projections of the latter part of a size toenlarge a key seat to the approximate size of the larger collar end 29.Of course, the above-indicated sizes of collar projections may bevaried, providing the same enlarge a key seat, in successive stages,until said seat is large enough to pass the drill collar.

The means 13 is provided in the reaming collar 12 adjacent its lower endand is shown as comprising oppositely disposed openings 32 substantiallylarger than keys 24 and in which said keys are adapted to be disposed.Each opening 32 is formed to have a straight side 33 and a bottom edgeor side that is formed with a sloping edge 34 at an angle substantiallythe same as that of key face 25. The shape of the other sides or facesof said openings 32 is immaterial, provided the keys 24 are freely andloosely received in said openings.

It will be noted from Fig. 3 that the keys project less than thethickness of the collar. A commensurately shallow slot 35 extends fromthe bottom of each opening. 32 to the lower end of the collar, as bestseen in Fig. 5, and is of a width and depth to freely pass said keys. Asshown, each said slot 35 is circumferentially spaced from walls 33, thesloping faces 34 extending between the lower ends of said walls and saidslots. It will be obvious that the depth of said keys 24 may approximatethe thickness of the reaming collar, in which case slots 35 will be cutcompletely through said collar.

Operation During normal rotary drilling, the reaming collar ispositioned, as shown in Fig. 1, resting on shoulder 22 and with keys 24in collar openings 32. Said collar merely rotates with the drill stringin a clockwise direction, as seen from above, so that the threadedjoints in the drill string may be maintained.

Should the well bore have a key seat therein, when withdrawing the drillstring the upper collar part 28 is wedged first in said seat andprevents continuation of the with drawal. In such case, a clockwisetorque is placed on the drill string in some usual manner, as by tongs,from above. This brings the keys 24 into firm engagement with the sides33 of openings 32 in the collar.

Since the drill collar 12 is firmly wedged in the key seat, the torqueapplied to the drill string results in said string. winding uptorsionally in the manner of a torsional spring. While this torque ismaintained, the string is lowered. As a result of such lowering, thesloping faces 25 of keys 24 come to rest on the sloping faces 34 of 4 Iopenings 32. It will be realized that the drill string, initiallyelongated because in free suspension, becomes foreshortened as thedownward movement of the keys is arrested and more and more of thestring weight comes to bear on the points of engagement between faces 25and 34.

The weight of a drill string will vary with its length but, in any case,will be many thousands of pounds. This weight on the sloping faces 34 ofthe collar 12 gradually overcomes the torsional force on the drillstring and the keys 24 of the latter cam downwardly along sloping faces34 until said keys lose contact with said sloping. faces. Thus, theforce of the weight of the string becomes effective to overcome thetorsional force of the string, the keys 24 moving counter to thedirection of the torsion by reason of said cam-wedging engagement offaces 25 and 34. Then, as keys 24 become aligned with slots 35 in collar12, the full weight of the drill string is released with trigger-likesuddenness and the string drops off the sloping faces 35 and causesshoulder 20 of the drill string to strike the top edge of collar 12 witha sudden force represented by the full Weight of the drill string. Thisforce is normally great enough to dislodge said collar from a key seat.In any case, the above can be repeated, if necessary, until dislodgementresults. The repeat operation starts with an upward withdrawal of thestring until keys 24 encounter the lower edge of the collar 12. Then, byrotating the string while continuing upward withdrawal thereof, the keysfind and enter slots 35; upward withdrawal of the string is arrestedwhen the keys encounter the upper edges 32a of openings 32. Now, torsionis applied to the string,

as before, and the string lowered, to repeat the jarring operation.

While jarring devices have, heretofore, employed a drop of the drillstring, the jarring forces were conventionally applied by alternateraising and releasing of the string from above. There was no suddenrelease of the full force of the weight as in the present instance, butrather a gradual use of the weight because of the elongation andcontraction inherent in a long drill string.

When dislodged, as above, the reaming collar 12 may first fall onto keys24. However, only a partial rotation of the string is needed to allowthe keys to slip upwardly into openings 32. Now shoulder 22 encountersthe lower edge of the reaming collar 12, as before. Since torsionalforce on the collar part 28 had effected its dislodgement from the keyseat, the collar will pass upwardly as the drill string is being againwithdrawn to bring the intermediate part 30 of the collar intoengagement with said seat. Now, if this part becomes wedged, the keyseat is further enlarged by repeating the above-described operation. Ofcourse, if the keys 24 do not find grooves 35, when the string is beingwithdrawn, said keys will serve the same purpose as shoulder 22 andcarry the collar 12 upward. In this case, before again starting thejarring operation, the keys are withdrawn, as before described, intoengagement with the upper edges 32a of openings 32. To minimize frictionbetween the sloping face 26 of each key and the lower edge 36 of thecollar when the string is being upwardly moved, a sloping face 37 isprovided where said lower collar edge 36 is adjacent to each slot 35.Thus, the keys are easily led or guided into slots 35 because the corner38 of each key is guided into engagement with the longitudinal edge 39of each slot and inadvertent slipping of the keys past the slots isobviated.

From the foregoing, it will be realized that the key seat is finallyenlarged by the lower end of the reaming collar to a size that willpermit free upward passage of the drill collar 15. Said successiveoperations need only be performed if wedging occurs since there may beinstances when the next larger portion of the collar may,

during raising of the drill string, pass through the key seat aspreviously enlarged.

It will be evident from the foregoing that a key seat in a well bore isenlarged in successive stages to a size that will freely pass drillcollar and the bit carried thereby.

While sloping face 34 is shown as of relatively small extent, it will beclear that the same actually constitutes a portion of a helix alongwhich key face 25 may move under force of the weight of the drillstring. Therefore, it is intended that face 34 represent a helical camwhich may be short, as shown, or substantially longer in extent.Broadly, therefore, face 34 may be considered as weightarresting meansthat yields to efli'ect sudden release between mandrel 18 and reamingsleeve or collar 12 while torsion is applied to a string in which saidcollar is embodied and the weight of the string is released from aboveand is supported by the arresting means.

Because of the ability to free the drill string from the reaming collar,it is a simple matter to determine whether inability to withdraw thestring results from wedging of the collar in a key seat. By slacking 01fon the string to lower the keys 24 below the reaming collar, such acheck can be made since, if the string can be freely rotated from above,the reaming collar is wedged in a key seat. If the string cannot berotated freely, then there is another cause that resists stringwithdrawal.

Prior well reams or key seat enlargers operate on the principle ofdislodging successively more elevated portions of a key seat and alwayson a constant diameter of enlargement. This disclosure includes a methodof key seat enlargement that is based, not on constant-diameterenlargement, but rather on enlargement to successively larger diametersin easy, tool-sparing stages.

While I have illustrated and described what I now contemplate to be thebest mode of carrying out my invention, the construction is, of course,subject to modification without departing from the spirit and scope ofthe invention. It is, therefore, not desired to restrict the inventionto the particular form of construction illustrated and described, but tocover all modifications that may fall within the scope of the appendedclaims.

Having thus described my invention, what I claim and desire to besecured by Letters Patent is:

1. A key seat enlarging tool comprising an elongated mandrel havingupper and lower shoulders, at reaming collar rotatably and slidablymounted on said mandrel, a key on said mandrel adjacent but spacedupwardly from said lower shoulder, said reaming collar being normally inengagement with said lower shoulder and having a recess Wider than saidkey, receiving said key, and provided with a side face opposed to a sideof said key to establish a rotary driving connection between saidmandrel and collar, said collar having a keyway therein extending fromthe lower end thereof into said recess and being circumferentiallyoffset from said side face of said recess, the length of said collarbeing less than the distance between said key and the upper shoulder.

2. A key seat enlarging tool as defined in claim 1 wherein a first camsurface slopes downwardly from the lower end of said side face to theupper end of the adjacent side of said keyway, said key having acorresponding cam surface at its lower edge arranged to slidably engagesaid first cam surface.

References Cited in the file of this patent UNITED STATES PATENTS1,701,427 Shields Feb. 5, 192.9 2,107,547 Pyle Feb. 8, 1938 2,212,067Hofioss Aug. 20, 1940 2,572,839 McClinton Oct. 30, 1951 2,620,164 BurrisDec. 2, 1952 2,665,887 Shelton Jan. 12, 1954 OTHER REFERENCES Burris KeySeat Wiper Drill Collar Assembly, by J. J. Burris, October 1946. (Copyin Div. 49.)

